Method of making linear alkylbenzenes

ABSTRACT

A method of producing a linear alkylbenzene that includes introducing an olefin into an aromatic stream to form a mixture; processing the mixture in a shear device at a shear rate greater than about 20,000 s −1  to form a dispersion; and reacting the dispersion in the presence of a catalyst in a reactor vessel to form a linear alkylbenzene product stream, wherein the reactor vessel is maintained at a bulk reaction temperature in the range of about 0° C. to about 60° C.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/144,459, filed Jun. 23, 2008, which applicationclaims the benefit under 35 U.S.C. §119(e) of U.S. Provisional PatentApplication No. 60/946,501, filed Jun. 27, 2007. The disclosure of eachapplication is hereby incorporated herein by reference in entirety forall purposes.

BACKGROUND

1. Field of the Invention

This invention relates generally to the field of chemical reactions.More specifically, the invention relates to methods of making linearalkylbenzenes, that is, an alkyl aromatic compound wherein an atom ofhydrogen in a benzene ring is substituted by a paraffin hydrocarbonchain, incorporating high shear mixing.

2. Background of the Invention

Alkylbenzenes have a wide range of technical uses. For instancealkylbenzenes with a number of carbon atoms in the side chain rangingbetween 8 and 16 are intermediates in the manufacture of sulfonateddetergents. Alkylbenzene derivatives, such as alkyl benzene sulfonates,are among others, used in detergent and surfactant product applications.Environmental legislation requires that these products be biodegradable.Alkylbenzenes with a branched aliphatic chain are not decayed, departingfrom such with a linear chain, by aerobic bacteria and therefore tend toaccumulate in water discharged from plants employing such detergents. Itis well known that, to be biodegradable, it is important for the alkylchain to be linear, i.e. with very little or no branching and low, ifany, quaternary carbons. As such, linear alkylbenzenes have emerged asthe dominant detergent intermediate since the early 1960s driven by theenvironmental need to produce biodegradable detergents.

The commercial development of linear alkylbenzenes has focused on theextraction of high purity linear paraffins derived from hydrotreatedkerosene feedstock. Initially, these linear paraffins weredehydrogenated, at less than complete conversion, to linear internalmono-olefins. The dehydrogenation effluent, a mixture of olefins andparaffins, was used to alkylate benzene using hydrofluoric acid as thecatalyst to produce linear alkylbenzenes. The conversion of the olefinsto alkylbenzenes facilitated the separation of the unreacted linearparaffins by fractionation and their recycle to the dehydrogenationprocess. The resulting linear alkylbenzene product became the syntheticdetergent intermediate for the production of linear alkylbenzenesulfonate, a major biodegradable synthetic surfactant. Linearalkylbenzene sulfonate remains the dominant workhorse surfactant but itsposition in North America and Western Europe is constantly challenged bydetergent alcohol derivatives.

This detergent alkylate is formed by the reaction of an aromatichydrocarbon with an olefinic hydrocarbon having from about 6 to 20carbon atoms per molecule. A better quality detergent precursor normallyresults from the use of olefinic hydrocarbons having from 10-15 carbonatoms per molecule. In an embodiment, the alkylation reaction may be aFriedel-Crafts alkylation. Linear alkylbenzenes have been producedcommercially via the following routes: 1) Dehydrogenation of n-paraffinsto internal olefins followed by alkylation with benzene using ahydrofluoric acid (HF) catalyst; 2) Dehydrogenation of n-paraffins tointernal olefins followed by alkylation with benzene using a fixed-bedof acidic, non-corrosive solid catalyst; 3) Chlorination of n-paraffinsto form monochloroparaffins. The monochloroparaffins are subsequentlyalkylated with benzene in the presence of an aluminum chloride (AlCl₃)catalyst; and 4) Chlorination of n-paraffins to form chlorinatedparaffins. The chlorinated paraffins are subsequently dehydrochlorinatedto olefins (both alpha and internal). These olefins subsequently undergobenzene alkylation in the presence of an aluminum chloride catalyst. Thepreferred aromatic hydrocarbon is benzene but other hydrocarbonsincluding toluene, the xylene and ethylbenzene may also be alkylated inthe same manner

The preparation of linear alkylbenzenes by the catalytic alkylation ofbenzene with n-olefins may occur in the presence, of Lewis acidcatalysts, such as, aluminum chloride boron triflouide, hydrofluoricacid, sulfuric acid, phosphoric anhydride etc. In industrial practicethe two major catalysts for the alkylation of benzene with higher alphaor internal mono-olefins (C₁₀-C₁₆ detergent range olefins), are aluminumchloride and hydrofluoric acid. The HF-based process has become moreprevalent than ones based on aluminum chloride. Alternatively, a mixtureof n-olefins and chloroparrafins may be used as the alkylating agent ofbenzene, in the presence of aluminum chloride or aluminum in powder formas a catalyst.

The use of HF and AlCl₃ catalysts presents many challenges. For example,aluminum chloride is difficult to separate after reaction and produces alarge amount of waste effluent. The desirability of avoiding the use ofpotentially hazardous chemicals like HF has motivated the development ofimproved mechanisms for the production of alkylbenzenes. The advances inmaking linear alkylbenzenes have focused on catalyst development ordifferent reaction pathways. Reactions which involve olefinichydrocarbons and are catalyzed by hydrogen fluoride usually proceed at avery fast rate. To reduce the amount of olefin polymerization and topromote production of a mono-alkylated aromatic product, the reactantsare normally subjected to vigorous mixing and agitation at the initialcontacting of the olefinic reactant with the hydrogen fluoride andaromatic reactant. The desired result is a uniform dispersion andintimate contacting of hydrocarbon and hydrogen fluoride phases and theavoidance of the formation of localized high temperatures or highhydrogen fluoride concentrations. Nothing has dealt with improving themixing and dispersion of the reactants for lowering reaction time orlowering reaction pressure and temperature.

Consequently, there is a need for accelerated methods for making linearalkylbenzenes by improving the mixing of olefins into the liquid benzenephase.

BRIEF SUMMARY

Methods and systems for the preparation of linear alkylbenzenes aredescribed herein. The methods and systems incorporate the novel use of ahigh shear device to promote dispersion and solubility of olefins in thearomatic liquid phase. The high shear device may allow for lowerreaction temperatures and pressures and may also reduce alkylation time.Further advantages and aspects of the disclosed methods and system aredescribed below.

In an embodiment, a method of making a linear alkylbenzene comprisesintroducing one or more olefins into an aromatic stream to form areactant stream. The method also comprises subjecting said reactantstream to a shear rate of greater than about 20,000 s⁻¹ with a highshear device. Furthermore, the method comprises contacting the reactantstream with a catalyst to form a linear alkylbenzene.

In an embodiment, a system for the production of a linear alkylbenzenecomprises at least one high shear device comprising a rotor and astator. The rotor and the stator are separated by a shear gap in therange of from about 0.02 mm to about 5 mm. The shear gap is a minimumdistance between the rotor and the stator. The high shear device iscapable of producing a tip speed of the at least one rotor of greaterthan about 23 m/s (4,500 ft/min). In addition, the system comprises apump configured for delivering a liquid stream to the high shear device.The system also comprises an alkylation reactor coupled to the highshear device. The reactor is configured for receiving said liquid streamfrom said high shear device. Introducing an olefin into an aromaticstream. The method also comprises flowing the olefin and the aromaticstream through a high shear device so as to form dispersion with bubblesless than about 5 μm in diameter.

Embodiments disclosed herein pertain to a method of producing a linearalkylbenzene that includes introducing an olefin into an aromatic streamto form a mixture; processing the mixture in a shear device at a shearrate greater than about 20,000 s⁻¹ to form a dispersion; and reactingthe dispersion in the presence of a catalyst in a reactor vessel to forma linear alkylbenzene product stream, wherein the reactor vessel ismaintained at a bulk reaction temperature in the range of about 0° C. toabout 60° C. The reaction vessel may be an alkylation reactor configuredfor receiving the dispersion from the shear device. The olefin mayinclude from 1 to 10 carbon atoms.

Methods of disclosure may include separating linear alkylbenzene fromthe linear alkylbenzene product stream. The separated linearalkylbenzene may include dodecylbenzene. The method may includecontacting the aromatic stream with a second catalyst before introducingthe olefin. In some aspects, the formed dispersion may include gasbubbles with a mean diameter of less than 5 μm. In other aspects, themean diameter may be less than 1.5 μm.

The produced linear alkylbenzene may have the formula:

-   -   wherein R is an alkyl group having from 1 to 20 carbon atoms and        R may be branched or unbranched.

At least one of the catalyst and the second catalyst may be a Lewisacid. At least one of the catalyst and the second catalyst may includean aluminum halide, a titanium halide, a zirconium halide, an ironhalide, a vanadium halide, a chromium halide, and combinations thereof.In aspects, the shear device may include at least one rotor and at leastone stator separated by a shear gap in the range of from about 0.02 mmto about 5 mm. In other aspects, the shear device may be capable ofproducing a tip speed of the at least one rotor in the range of greaterthan about 23 m/s.

Other embodiments of the disclosure pertain to a method of producing alinear alkylbenzene that may include introducing an olefin into anaromatic stream to form a mixture; processing the mixture in a sheardevice to form a dispersion; and reacting the dispersion in the presenceof a catalyst in a reactor vessel to form a linear alkylbenzene productstream. In aspects, the olefin includes from 1 to 10 carbon atoms. Inother aspects, the aromatic stream includes at least one selected fromthe group consisting of benzene, toluene, phenol, aniline, xylene, andethylbenzene. The dispersion may include olefin gas bubbles with anaverage gas bubble diameter of less than about 5 μm.

The method may also include transferring the linear alkylbenzene productstream to a stripper; and operating the stripper to producesubstantially pure linear alkylbenzene. The method may also includerecycling at least a portion of the linear alkylbenzene product streamor substantially pure linear alkylbenzene to the shear device. The sheardevice may have at least two rotor-stator generators. The catalyst maybe selected from the group consisting of hydrofluoric acid and aluminumchloride.

Yet other embodiments of the disclosure pertain to a method of producinga linear alkylbenzene that may include introducing one or more olefinsinto an aromatic stream to form a reactant stream; processing thereactant stream in a high shear device to produce a sheared productstream, wherein the shear device comprises at least one generatorcomprising a rotor and a complementarily-shaped stator; reacting thesheared product stream in the presence of a catalyst to form a linearalkylbenzene product stream, wherein said linear alkylbenzene is formedat a temperature in the range of from about 0° C. to about 60° C.; andseparating linear alkylbenzene from the linear alkylbenzene productstream.

In aspects, the sheared product may include gas bubbles with a meandiameter of less than 100 nm. In other aspects, the catalyst may beselected from the group consisting of hydrofluoric acid and aluminumchloride. The olefin may include from 1 to 10 carbon atoms. The aromaticstream may include at least one selected from the group consisting ofbenzene, toluene, phenol, aniline, xylene, and ethylbenzene.

The method may include recycling at least a portion of the shearedproduct stream, the linear alkylbenzene product stream, andsubstantially pure linear alkylbenzene to the shear device. In aspects,the shear device may include a second rotor-stator generator.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter that form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand the specific embodiments disclosed may be readily utilized as abasis for modifying or designing other structures for carrying out thesame purposes of the present invention. It should also be realized bythose skilled in the art that such equivalent constructions do notdepart from the spirit and scope of the invention as set forth in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiments of theinvention, reference will now be made to the accompanying drawings inwhich:

FIG. 1 illustrates a general flow diagram of an embodiment of a processusing a high shear device.

FIG. 2 illustrates a longitudinal cross-section view of a multi-stagehigh shear device, as employed in an embodiment of the system of FIG. 1.

NOTATION AND NOMENCLATURE

Certain terms are used throughout the following description and claimsto refer to particular system components. This document does not intendto distinguish between components that differ in name but not function.

In the following discussion and in the claims, the terms “including” and“comprising” are used in an open-ended fashion, and thus should beinterpreted to mean “including, but not limited to . . . ”.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The process of the present disclosure for the linear alkylation ofbenzene comprises utilization of an external high shear mechanicaldevice to provide rapid contact and mixing of chemical ingredients in acontrolled environment in the reactor/mixer device. The high sheardevice is a mechanical reactor, mixer, or mill. The high shear devicereduces the mass transfer limitations on the reaction and thus increasesthe overall reaction rate.

Chemical reactions involving liquids, gases and solids rely on the lawsof kinetics that involve time, temperature, and pressure to define therate of reactions. In cases where it is desirable to react two (or more)raw materials of different phases (e.g. solid and liquid; liquid andgas; solid, liquid and gas), one of the limiting factors in controllingthe rate of reaction involves the contact time of the reactants. As usedherein, “multi-phase” refers to a reaction involving reactions with twoor more different phases. In the case of heterogeneously catalyzedreactions there is the additional rate limiting factor of having thereacted products removed from the surface of the catalyst to enable thecatalyst to catalyze further reactants.

The alkylation of benzene with an olefin in the presence of a catalystis a multiphase reaction. During the multiphase reaction, the phasesseparate spontaneously. It is desirable to provide the requisite intensemixing and contact time and to provide a means of allowing thehydro-carbon hydrogen fluoride mixture to separate into the respectiveliquid phases. The presently disclosed method and system whereby the twophases are intimately mixed to form an emulsion enhances contact surfacebetween the reaction components, thus enhancing the reaction.

“Emulsion” refers to a liquefied mixture that contains twodistinguishable substances (or “phases”) that will not readily mix anddissolve together. Most emulsions have a “continuous” phase (or“matrix”), which holds therein discontinuous droplets, bubbles, and/orparticles of the other phase or substance. Emulsions may be highlyviscous, such as slurries or pastes, or may be foams, with tiny gasbubbles suspended in a liquid. As used herein, the term “emulsion”encompasses continuous phases comprising gas bubbles, continuous phasescomprising particles (e.g., solid catalyst), continuous phasescomprising droplets of a fluid that is substantially insoluble in thecontinuous phase, and combinations thereof.

In conventional reactors, contact time for the reactants and/or catalystis often controlled by mixing which provides contact with two or morereactants involved in a chemical reaction. Embodiments of the disclosedmethod comprise an external high shear device to decrease mass transferlimitations and thereby more closely approach kinetic limitations. Whenreaction rates are accelerated, residence times may be decreased,thereby increasing obtainable throughput. Alternatively, where thecurrent yield is acceptable, decreasing the required residence timeallows for the use of lower temperatures and/or pressures thanconventional processes. Furthermore, in homogeneous reactions, thedisclosed process could be used to provide for uniform temperaturedistribution within the reactor thereby minimizing potential sidereactions.

System for the Production of Linear Alkylbenzenes.

A high shear alkylbenzene production system will now be described inrelation to FIG. 1, which is a process flow diagram of an embodiment ofa high shear system (HSS) 100 for the production of alkylbenzene viaalkylation of benzene with olefins in the presence of a catalyst. Thebasic components of a representative system include external high sheardevice (HSD) 140, vessel 110, pump 105 and fluidized or fixed bed 142.As shown in FIG. 1, the high shear device is located external tovessel/reactor 110. Each of these components is further described inmore detail below. Line 121 is connected to pump 105 for introducingreactant. Line 113 connects pump 105 to HSD 140, line 118 connects HSD140 to fluidized or fixed bed 142 and line 119 connects bed to vessel110. Line 122 is connected to line 113 for introducing anoxygen-containing gas (e.g., O₂ or air). Line 117 is connected to vessel110 for removal of unconverted reactants, and other by-products.

High shear devices (HSDs) such as a high shear device, or high shearmill, are generally divided into classes based upon their ability to mixfluids. Mixing is the process of reducing the size of inhomogeneousspecies or particles within the fluid. One metric for the degree orthoroughness of mixing is the energy density per unit volume that themixing device generates to disrupt the fluid particles. The classes aredistinguished based on delivered energy density. There are three classesof industrial mixers having sufficient energy density to consistentlyproduce mixtures or emulsions with particle or bubble sizes in the rangeof 0 to 50 microns.

In the first class of high energy devices, referred to as homogenizationvalve systems, fluid to be processed is pumped under very high pressurethrough a narrow-gap valve into a lower pressure environment. Thepressure gradients across the valve and the resulting turbulence andcavitation act to break-up any particles in the fluid. These valvesystems are most commonly used in milk homogenization and can yieldaverage particle sizes in the 0-1 micron range.

At the opposite end of the energy density spectrum is the third class ofdevices referred to as low energy devices. These systems usually havepaddles or fluid rotors that turn at high speed in a reservoir of fluidto be processed, which in many of the more common applications is a foodproduct. These low energy systems are customarily used when averageparticle sizes of greater than 20 microns are acceptable in theprocessed fluid.

Between low energy—high shear devices and homogenization valve systems,in terms of the mixing energy density delivered to the fluid, arecolloid mills, which are classified as intermediate energy devices. Thetypical colloid mill configuration includes a conical or disk rotor thatis separated from a complementary, liquid-cooled stator by aclosely-controlled rotor-stator gap, which is commonly between 0.025 mmand 10.0 mm. Rotors are usually driven by an electric motor through adirect drive or belt mechanism. Many colloid mills, with properadjustment, can achieve average particle sizes of 0.1 to 25 μm in theprocessed fluid. These capabilities render colloid mills appropriate fora variety of applications including colloid and oil/water-based emulsionprocessing such as that required for cosmetics, mayonnaise,silicone/silver amalgam formation, or roofing-tar mixing.

An approximation of energy input into the fluid (kW/L/min) can beestimated by measuring the motor energy (kW) and fluid output (L/min).Tip speed is the circumferential distance traveled by the tip of therotor per unit of time. Tip speed is thus a function of the rotordiameter and the rotational frequency. Tip speed (in meters per minute,for example) may be calculated by multiplying the circumferentialdistance transcribed by the rotor tip, 2πR, where R is the radius of therotor (in meters, for example) times the frequency of revolution (inrevolutions per minute). A colloid mill, for example, may have a tipspeed in excess of 22.9 msec and may exceed 40 msec. For the purposes ofthis disclosure, the term “high shear” refers to mechanical rotor statordevices (e.g., colloid mills or rotor/stator mixers) that are capable oftip speeds in excess of 5.1 msec and require an external mechanicallydriven power device to drive energy into the stream of materials to bereacted. For example, in HSD 140, a tip speed in excess of 22.9 msec isachievable, and may exceed 40 msec. In some embodiments, HSD 140 iscapable of delivering at least 300 L/h with a power consumption of about1.5 kW at a nominal tip speed of at least 22.9 msec.

HSD 140 combines high tip speeds with a very small shear gap to producesignificant friction on the material being processed. Accordingly, alocal pressure in the range of about 1034.2 MPa and elevatedtemperatures at the tip of the shear mixer are produced duringoperation. In some embodiments, the energy expenditure of the high sheardevice is greater than 1000 W/m³. In embodiments, the energy expenditureof HSD 140 is in the range of from about 3000 W/m³ to about 7500 W/m³.The shear rate is the tip speed divided by the shear gap width (minimalclearance between the rotor and stator). The shear rate generated in HSD40 may be greater than 20,000 s⁻¹. In some embodiments the shear rate isat least 1,600,000 s⁻¹. In embodiments, the shear rate generated by HSD140 is in the range of from 20,000 s⁻¹ to 100,000 s⁻¹. For example, inone application the rotor tip speed is about 40 msec and the shear gapwidth is 0.0254 mm, producing a shear rate of 1,600,000 s⁻¹. In anotherapplication the rotor tip speed is about 22.9 msec and the shear gapwidth is 0.0254 mm producing a shear rate of about 902,000 s⁻¹

HSD 140 is capable of highly mixing the reactants and liquid media, someof which would normally be immiscible, at conditions such that at leasta portion of the monomer reacts to produce a polymerization product. Insome embodiments, HSD 140 comprises a colloid mill. Suitable colloidalmills are manufactured by IKA® Works, Inc. Wilmington, N.C. and APVNorth America, Inc. Wilmington, Mass., for example. In some instances,HSD 140 comprises the Dispax Reactor® of IKA® Works, Inc. Several modelsare available having various inlet/outlet connections, horsepower,nominal tip speeds, output rpm, and nominal flow rate. Selection of aparticular device will depend on specific throughput requirements forthe intended application, and on the desired particle size in the outletdispersion from the high shear device. In some embodiments, selection ofthe appropriate mixing tools (generators) within HSD 140 may allow forcatalyst size reduction/increase in catalyst surface area.

The high shear device comprises at least one revolving element thatcreates the mechanical force applied to the reactants. The high sheardevice comprises at least one stator and at least one rotor separated bya clearance. For example, the rotors may be conical or disk shaped andare separated from a complementary-shaped stator comprising a pluralityof circumferentially-spaced high shear openings. For example, the rotorsmay be conical or disk shaped and may be separated from acomplementary-shaped stator; both the rotor and stator may comprise aplurality of circumferentially-spaced teeth. In some embodiments, thestator(s) are adjustable to obtain the desired gap between the rotor andthe stator of each generator (rotor/stator set). Grooves in the rotorand/or stator may change directions in alternate stages for increasedturbulence. Each generator may be driven by any suitable drive systemconfigured for providing the necessary rotation.

In some embodiments, the minimum clearance between the stator and therotor is in the range of from about 0.0254 millimeters to about 3.175millimeters. In certain embodiments, the minimum clearance between thestator and rotor is about 1.524 mm. In certain configurations, theminimum clearance between the rotor and stator is at least 1.778 mm. Theshear rate produced by the high shear device may vary with longitudinalposition along the flow pathway. In some embodiments, the rotor is setto rotate at a speed commensurate with the diameter of the rotor and thedesired tip speed. In some embodiments, the colloidal mill has a fixedclearance between the stator and rotor. Alternatively, the colloid millhas adjustable clearance.

In some embodiments, HSD 140 comprises a single stage dispersing chamber(i.e., a single rotor/stator combination, a single generator). In someembodiments, high shear device 140 is a multiple stage inline colloidmill and comprises a plurality of generators. In certain embodiments,HSD 140 comprises at least two generators. In other embodiments, highshear device 140 comprises at least 3 high shear generators. In someembodiments, high shear device 140 is a multistage mixer whereby theshear rate (which varies proportionately with tip speed and inverselywith rotor/stator gap) varies with longitudinal position along the flowpathway, as further described herein below.

In some embodiments, each stage of the external high shear device hasinterchangeable mixing tools, offering flexibility. For example, the DR2000/4 Dispax Reactor® of IKA® Works, Inc. Wilmington, N.C. and APVNorth America, Inc. Wilmington, Mass., comprises a three stagedispersing module. This module may comprise up to three rotor/statorcombinations (generators), with choice of fine, medium, coarse, andsuper-fine for each stage. This allows for creation of dispersionshaving a narrow distribution of the desired particle size. In someembodiments, each of the stages is operated with super-fine generator.In some embodiments, at least one of the generator sets has arotor/stator minimum clearance of greater than about 5.08 mm. Inalternative embodiments, at least one of the generator sets has aminimum rotor/stator clearance of greater than about 1.778 mm.

External high shear device 140 may be cooled as known to those of skillin the art. Liquid reactant, for example, may be used to cool the sealand thereby preheated as desired.

In embodiments, external high shear device 140 serves to intimately mixa liquid solution with a liquid reactant stream 122. In embodiments, theresultant dispersion comprises microbubbles. In embodiments, theresultant dispersion comprises bubbles in the submicron size. Inembodiments, the resultant dispersion has an average bubble size lessthan about 1.5 μm. In embodiments, the bubble size is from about 0.4 toabout 1.5 μm. In embodiments, the high shear mixing produceshydrobubbles capable of remaining dispersed at atmospheric pressure forabout 15 minutes.

As used herein, a high shear device is capable of dispersing ortransporting, one phase or ingredient (e.g. liquid, solid, gas) into amain continuous phase (e.g. liquid) with which it would normally beimmiscible or insoluble. In embodiment, a high shear device is a colloidmill for dispersing gas into an aqueous liquid, hereby creating anemulsion, or foam.

Referring now to FIG. 2, there is presented a schematic diagram of ahigh shear device 200. High shear device 200 comprises at least onerotor-stator combination. The rotor-stator combinations may also beknown as generators 220, 230, 240 or stages without limitation. The highshear device 200 comprises at least three generators.

The first generator 220 comprises rotor 222 and stator 227. The secondgenerator 230 comprises rotor 223, and stator 228; the third generatorcomprises rotor 224 and stator 229. For each generator the rotor isrotatably driven by input 250. Stator 227 is fixably coupled to the highshear device wall 255.

The generators include gaps between the rotor and the stator. The firstgenerator 220, comprises a first gap 225; the second generator 230comprises a second gap 235; and the third generator 240 comprises athird gap 245. The gaps 225, 235, 245 are between about 0.025 mm and 10mm wide. Alternatively, the process comprises utilization of a highshear device 200 wherein the gaps 225, 235, 245 are between about 0.5 mmand about 2.5 mm. In certain instances the gap is maintained at about1.5 mm. Alternatively, the gaps 225, 235, 245 are different betweengenerators 220, 230, 240. In certain instances, the gap 225 for thefirst generator 220 is greater than about the gap 235 for the secondgenerator 230, which is in turn greater than about the gap 245 for thethird generator. Each generator of the high shear device 200 hasinterchangeable mixing tools, offering flexibility.

Additionally, the width of the gaps 225, 235, 245 may comprise a coarse,medium, fine, and super-fine characterization. Rotors 222, 223, and 224and stators 227, 228, and 229 may be toothed designs. Each generator maycomprise two or more sets of rotor-stator teeth, as known in the art.Rotors 222, 223, and 224 may comprise a number of rotor teethcircumferentially spaced about the circumference of each rotor. Stators227, 228, and 229 may comprise a number of stator teethcircumferentially spaced about the circumference of each stator. Therotor and the stator may be of any suitable size. In one embodiment, theinner diameter of the rotor is about 64 mm and the outer diameter of thestator is about 60 mm. In other embodiments, the inner diameter of therotor is about 11.8 cm and the outer diameter of the stator is about15.4 cm. The rotor and stator may have alternate diameters in order toalter the tip speed and shear pressures. In certain embodiments, each ofthree stages is operated with a super-fine generator, comprising a gapof between about 0.025 mm and about 3 mm. When a feed stream 205including solid particles is to be sent through high shear device 200,the appropriate gap width is first selected for an appropriate reductionin particle size and increase in particle surface area. In embodiments,this is beneficial for increasing catalyst surface area by shearing anddispersing the particles.

High shear device 200 is fed a reaction mixture comprising the feedstream 205. Feed stream 205 comprises an emulsion of the dispersiblephase and the continuous phase. Feed stream 205 may include aparticulate solid catalyst component. Feed stream 205 is pumped throughthe generators 220, 230, 240, such that product dispersion 210 isformed. In each generator, the rotors 222, 223, 224 rotate at high speedrelative to the fixed stators 227, 228, 229. The rotation of the rotorspumps fluid, such as the feed stream 205, between the outer surface ofthe rotor 222 and the inner surface of the stator 227 creating alocalized high shear condition. The gaps 225, 235, 245 generate highshear forces that process the feed stream 205. The high shear forcesbetween the rotor and stator functions to process the feed stream 205 tocreate the product dispersion 210.

The product dispersion 210 of gas particles, or bubbles, in a liquidcomprises an emulsion. In embodiments, the product dispersion 210 maycomprise a dispersion of a previously immiscible or insoluble gas,liquid or solid into the continuous phase. The product dispersion 210has an average gas particle, or bubble, size less than about 1.5 μm;preferably the bubbles are sub-micron in diameter. In certain instances,the bubble size is from about 0.1 μm to about 1.0 μm. The high sheardevice 200 produces a gas emulsion capable of remaining dispersed atatmospheric pressure for about 15 minutes. For the purpose of thisdisclosure, an emulsion of gas particles, or bubbles, in the dispersedphase in product dispersion 210 that are less than 1.5 μm in diametermay comprise a micro-foam.

The high shear device 200 produces a gas emulsion capable of remainingdispersed at atmospheric pressure for at least about 15 minutes. For thepurpose of this disclosure, an emulsion of gas particles, or bubbles, inthe dispersed phase in product dispersion 210 that are less than 1.5 μmin diameter may comprise a micro-foam. Not to be limited by a specifictheory, it is known in emulsion chemistry that sub-micron particles, orbubbles, dispersed in a liquid undergo movement primarily throughBrownian motion effects. The bubbles in the emulsion of productdispersion 210 created by the high shear device 200 may have greatermobility through boundary layers of solid catalyst particles, therebyfacilitating and accelerating the catalytic reaction through enhancedtransport of reactants.

The rotor is set to rotate at a speed commensurate with the diameter ofthe rotor and the desired tip speed as described hereinabove. Transportresistance is reduced by incorporation of high shear device 200 suchthat the velocity of the reaction is increased by at least about 5%.Alternatively, the high shear device 200 comprises a high shear colloidmill that serves as an accelerated rate reactor (ARR). The acceleratedrate reactor comprises a single stage dispersing chamber. Theaccelerated rate reactor comprises a multiple stage inline dispersercomprising at least 2 stages.

Selection of the high shear device 200 is dependent on throughputrequirements and desired particle or bubble size in the outletdispersion 210. In certain instances, high shear device 200 comprises aDispax Reactor® of IKA® Works, Inc. Wilmington, N.C. and APV NorthAmerica, Inc. Wilmington, Mass. Model DR 2000/4, for example, comprisesa belt drive, 4M generator, PTFE sealing ring, inlet flange 1″ sanitaryclamp, outlet flange ¾″ sanitary clamp, 2 HP power, output speed of 7900rpm, flow capacity (water) approximately 300 l/h to approximately 700l/h (depending on generator), a tip speed of from 9.4 m/s to about 41m/s (about 1850 ft/min to about 8070 ft/min). Several alternative modelsare available having various inlet/outlet connections, horsepower,nominal tip speeds, output rpm, and nominal flow rate.

Without wishing to be limited to a particular theory, it is believedthat the level or degree of high shear mixing is sufficient to increaserates of mass transfer and may also produce localized non-idealconditions that enable reactions to occur that would not otherwise beexpected to occur based on Gibbs free energy predictions. Localized nonideal conditions are believed to occur within the high shear deviceresulting in increased temperatures and pressures with the mostsignificant increase believed to be in localized pressures. The increasein pressures and temperatures within the high shear device areinstantaneous and localized and quickly revert back to bulk or averagesystem conditions once exiting the high shear device. In some cases suchas in homogeneous liquid phase reactions, the high shear device inducescavitation of sufficient intensity to dissociate one or more of thereactants into free radicals, which may intensify a chemical reaction orallow a reaction to take place at less stringent conditions than mightotherwise be required. Cavitation may also increase rates of transportprocesses by producing local turbulence and liquid micro-circulation(acoustic streaming).

Vessel.

Vessel or reactor 110 is any type of vessel in which a multiphasereaction can be propagated to carry out the above-described conversionreaction(s). For instance, a continuous or semi-continuous stirred tankreactor, or one or more batch reactors may be employed in series or inparallel. In some applications vessel 110 may be a tower reactor, and inothers a tubular reactor or multi-tubular reactor. A catalyst inlet line115 may be connected to vessel 110 for receiving a catalyst solution orslurry during operation of the system.

Vessel 110 may include one or more of the following components: stirringsystem, heating and/or cooling capabilities, pressure measurementinstrumentation, temperature measurement instrumentation, one or moreinjection points, and level regulator (not shown), as are known in theart of reaction vessel design. For example, a stirring system mayinclude a motor driven mixer. A heating and/or cooling apparatus maycomprise, for example, a heat exchanger. Alternatively, as much of theconversion reaction may occur within HSD 140 in some embodiments, vessel110 may serve primarily as a storage vessel in some cases.

Heat Transfer Devices.

In addition to the above-mentioned heating/cooling capabilities ofvessel 110, other external or internal heat transfer devices for heatingor cooling a process stream are also contemplated in variations of theembodiments illustrated in FIG. 1. Some suitable locations for one ormore such heat transfer devices are between pump 105 and HSD 140,between HSD 140 and vessel 110, and between vessel 110 and pump 105 whensystem 100 is operated in multi-pass mode. Some non-limiting examples ofsuch heat transfer devices are shell, tube, plate, and coil heatexchangers, as are known in the art.

Pumps.

Pump 105 is configured for either continuous or semi-continuousoperation, and may be any suitable pumping device that is capable ofproviding greater than 2 atm pressure, preferably greater than 3 atmpressure, to allow controlled flow through HSD 140 and system 100. Forexample, a Roper Type 1 gear pump, Roper Pump Company (Commerce Ga.)Dayton Pressure Booster Pump Model 2P372E, Dayton Electric Co (Niles,Ill.) is one suitable pump. Preferably, all contact parts of pump 105are stainless steel, for example, 316 stainless steel. In embodiments,for example, wherein corrosive substances will be pumped (e.g. sulfuricacid) it may be desirable to have gold plated contact surfaces. In someembodiments of the system, pump 105 is capable of pressures greater thanabout 20 atm. In addition to pump 105, one or more additional, highpressure pump (not shown) may be included in the system illustrated inFIG. 1. For example, a booster pump, which may be similar to pump 105,may be included between HSD 140 and vessel 110 for boosting the pressureinto vessel 110.

Fluidized or Fixed Bed 142.

A fluidized or fixed bed may be used to carry out the chemical reaction.The bed can be operated either in: (a) upflow, at a liquid velocity suchthat the particles are fluidized, or (b) downflow, in which case the bedis fixed. This method is used to continuously move the catalyst betweenthe reactor and regeneration sections. A fluid bed is formed when aquantity of a solid particulate substance (usually present in a holdingvessel) is forced to behave as a fluid; usually by the forcedintroduction of pressurized fluid, often a gas through the particulatemedium. A fixed bed keeps the catalyst in one place converting thereactants to the desired product.

In embodiments, heating for a time is used to melt protective dropletson a catalyst. Additional reactants may be added over a time to bringthe reactants to a desired temperature, for example, 35° C. Inembodiments, the reactants are then introduced into high shear device140 where the reactants may continuously circulated and the reactioncontinues over a time period sufficient to produce a desired, forexample, a product having a specified purity or property value, afterwhich the reaction is terminated. In embodiments, pump 105 may be usedto provide a controlled flow throughout high shear device 140 and system100.

Production of Linear Alkylbenzenes.

Embodiments of the process and system 100 will now be described inrelation to accelerating the production of linear alkylbenzenes.Embodiments of the method comprise a process for alkylation of benzenesand its derivatives with olefins and paraffins in the presence of acatalyst dispersed in the liquid phase in a reactor 110. Embodiments ofthe process are characterized by the use of a high shear device 140 andintroduction of olefins to a catalyst-benzene mixture before enteringthe high shear device 140. Other derivatives of benzene that may be usedin conjunction with the process include without limitation, toluene,phenol, aniline, xylene, and the like. Generally, embodiments of theprocess are carried out by reacting a olefin containing about 1 to about10 carbon atoms with benzene and/or its derivatives to obtain thedesired alkylbenzene reaction product. In preferred embodiments, theolefin may be propylene or ethylene.

In a preferred embodiment, olefin may continuously be fed into aromaticstream 112 to form reactant stream 113. In high shear device 140, olefinand benzene are highly dispersed such that nanobubbles and microbubblesare formed for superior dissolution of olefin into solution. Oncedispersed, the dispersion may exit high shear device 140 at high sheardevice outlet line 118. Stream 118 may optionally enter fluidized orfixed bed 142 in lieu of a slurry catalyst process. However, in a slurrycatalyst embodiment, high shear outlet stream 118 may directly enterreactor 110 for alkylation. The reactant stream 113 may be maintained atthe specified reaction temperature, using cooling coils in the reactor110 to maintain reaction temperature. Alkylation products (e.g. linearalkylbenzenes) may be withdrawn at product stream 116. Product stream116 may be directed to one or more strippers (not shown) for removingcatalyst and purifying the alkylbenzene.

In an exemplary embodiment, the high shear device comprises a commercialdisperser such as IKA® model DR 2000/4, a high shear, three stagedispersing device configured with three rotors in combination withstators, aligned in series. The disperser is used to create thedispersion of olefins in the liquid medium comprising water (i.e., “thereactants”). The rotor/stator sets may be configured as illustrated inFIG. 2, for example. The combined reactants enter the high shear devicevia line 113 and enter a first stage rotor/stator combination havingcircumferentially spaced first stage shear openings. The coarsedispersion exiting the first stage enters the second rotor/stator stage,which has second stage shear openings. The reduced bubble-sizedispersion emerging from the second stage enters the third stagerotor/stator combination having third stage shear openings. Thedispersion exits the high shear device via line 118. In someembodiments, the shear rate increases stepwise longitudinally along thedirection of the flow. For example, in some embodiments, the shear ratein the first rotor/stator stage is greater than the shear rate insubsequent stage(s). In other embodiments, the shear rate issubstantially constant along the direction of the flow, with the stageor stages being the same. If the high shear device includes a PTFE seal,for example, the seal may be cooled using any suitable technique that isknown in the art. For example, the reactant stream flowing in line 113may be used to cool the seal and in so doing be preheated as desiredprior to entering the high shear device.

The rotor of HSD 140 is set to rotate at a speed commensurate with thediameter of the rotor and the desired tip speed. As described above, thehigh shear device (e.g., colloid mill) has either a fixed clearancebetween the stator and rotor or has adjustable clearance. HSD 140 servesto intimately mix the olefin vapor and the reactant liquid (i.e.,water). In some embodiments of the process, the transport resistance ofthe reactants is reduced by operation of the high shear device such thatthe velocity of the reaction (i.e. reaction rate) is increased bygreater than a factor of about 5. In some embodiments, the velocity ofthe reaction is increased by at least a factor of 10. In someembodiments, the velocity is increased by a factor in the range of about10 to about 100 fold. In some embodiments, HSD 140 delivers at least 300L/h with a power consumption of 1.5 kW at a nominal tip speed of atleast 4500 ft/min, and which may exceed 7900 ft/min (140 m/sec).Although measurement of instantaneous temperature and pressure at thetip of a rotating shear unit or revolving element in HSD 140 isdifficult, it is estimated that the localized temperature seen by theintimately mixed reactants may be in excess of 500° C. and at pressuresin excess of 500 kg/cm² under high shear conditions. The high shear mayresult in formation micron or submicron-sized bubbles. In someembodiments, the resultant dispersion has an average bubble size lessthan about 1.5 μm. Accordingly, the dispersion exiting HSD 140 via line118 comprises micron and/or submicron-sized gas bubbles. In someembodiments, the mean bubble size is in the range of about 0.4 μm toabout 1.5 μm. In some embodiments, the mean bubble size is less thanabout 400 nm, and may be about 100 nm in some cases. In manyembodiments, the microbubble dispersion is able to remain dispersed atatmospheric pressure for at least 15 minutes.

Once dispersed, the resulting olefin/water dispersion exits HSD 140 vialine 118 and feeds into vessel 110, as illustrated in FIG. 1. As aresult of the intimate mixing of the reactants prior to entering vessel110, a significant portion of the chemical reaction may take place inHSD 140, with or without the presence of a catalyst. Chemical reactionswhich involve olefinic hydrocarbons and which are catalyzed usuallyproceed at a very fast rate. To reduce the amount of olefinpolymerization and to promote the production of a mono-alkylatedaromatic product, the reactants are normally subjected to vigorousmixing and agitation at the point of initial contact of the olefinichydrocarbons and the liquid-phase catalyst (i.e. hydrogen fluoride). Thedesired result is a uniform dispersion and intimate contacting of thehydrocarbon and catalyst phases and the avoidance of localized hightemperatures or localized high concentrations of either the olefinichydrocarbon or the hydrogen fluoride. Accordingly, in some embodiments,reactor/vessel 110 may be used primarily for heating and separation ofvolatile reaction products from the alkylbenzene product. Alternatively,or additionally, vessel 110 may serve as a primary reaction vessel wheremost of the alkylbenzene product is produced. Vessel/reactor 110 may beoperated in either continuous or semi-continuous flow mode, or it may beoperated in batch mode. The contents of vessel 110 may be maintained ata specified reaction temperature using heating and/or coolingcapabilities (e.g., cooling coils) and temperature measurementinstrumentation. Pressure in the vessel may be monitored using suitablepressure measurement instrumentation, and the level of reactants in thevessel may be controlled using a level regulator (not shown), employingtechniques that are known to those of skill in the art. The contents arestirred continuously or semi-continuously.

The reaction may proceed under temperature and pressure conditionscommonly employed in such catalytic alkylation reactions. Inembodiments, the reaction temperature may range from about 0° C. toabout 80° C., preferably from about 30° C. to about 60° C. In addition,the reaction pressure may range from about 1 atm to about 10 atm,preferably from about 1 atm to about 5 atm.

In embodiments, the linear alkylbenzenes produced may have the followingformula:

where R is an alkyl group having from 1 to 20 carbon atoms and R may bebranched or unbranched.

In an alternative embodiment, high shear device 140 may serve as thealkylation reactor. That is, high shear device 140 may be heated to aspecified temperature to initiate the alkylation reaction. High sheardevice 140 increases the dispersion and solubility of olefin into theliquid aromatic phase for improved mass transfer and reaction kinetics.

Catalyst.

A catalyst may be introduced into the vessel via line 115, as an aqueousor nonaqueous slurry or stream. Alternatively, or additionally, catalystmay be added elsewhere in the system 100. For example, catalyst solutionor slurry may be injected into line 121. In general, the catalyst is analuminum halide or aluminum powder catalyst. In further embodiments, thecatalyst may comprise halides of titanium, zirconium, vanadium,chromium, iron, or combinations thereof. A suitable catalyst may also bebased on a Lewis acid, for example, HF and AlCl₃. Catalyst may be fedinto reactor 110 through catalyst feed stream 115. The catalystconcentration in the reactor appreciably affects the rate of alkylation.For example, the most advantageous concentration corresponds to 1 to 5gr. aluminum halide to liter of benzene. The amount of benzene presentwill during the alkylation will depend on the conversion selectivity toalkylbenzene. In general, the greater the stoichiometric excess ofbenzene, the greater the selectivity to alkylbenzene.

Multiple Pass Operation.

In the embodiment shown in FIG. 1, the system is configured for singlepass operation, wherein the output from vessel 110 goes directly tofurther processing for recovery of alkylbenzene product. In someembodiments it may be desirable to pass the contents of vessel 110, or aliquid fraction containing unreacted olefin, through HSD 140 during asecond pass. In this case, line 116 is connected to line 121 via dottedline 120, and the recycle stream from vessel 110 is pumped by pump 105into line 113 and thence into HSD 140. Additional olefins may beinjected via line 122 into line 113, or it may be added directly intothe high shear device (not shown).

Multiple High Shear Devices.

In some embodiments, two or more high shear devices like HSD 140, orconfigured differently, are aligned in series, and are used to furtherenhance the reaction. Their operation may be in either batch orcontinuous mode. In some instances in which a single pass or “oncethrough” process is desired, the use of multiple high shear devices inseries may also be advantageous. In some embodiments where multiple highshear devices are operated in series, vessel 110 may be omitted. In someembodiments, multiple high shear devices 140 are operated in parallel,and the outlet dispersions therefrom are introduced into one or morevessel 110.

While the preferred embodiments of the invention have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the invention. Theembodiments described and the examples provided herein are exemplaryonly, and are not intended to be limiting. Many variations andmodifications of the invention disclosed herein are possible and arewithin the scope of the invention. Accordingly, the scope of protectionis not limited by the description set out above, but is only limited bythe claims which follow, that scope including all equivalents of thesubject matter of the claims.

The discussion of a reference is not an admission that it is prior artto the present invention, especially any reference that may have apublication date after the priority date of this application. Thedisclosures of all patents, patent applications, and publications citedherein are hereby incorporated herein by reference in their entirety, tothe extent that they provide exemplary, procedural, or other detailssupplementary to those set forth herein.

1. A method of producing a linear alkylbenzene comprising: introducingan olefin into an aromatic stream to form a mixture; processing themixture in a shear device at a shear rate greater than about 20,000 s⁻¹to form a dispersion; and reacting the dispersion in the presence of acatalyst in a reactor vessel to form a linear alkylbenzene productstream, wherein the reactor vessel is maintained at a bulk reactiontemperature in the range of about 0° C. to about 60° C.
 2. The method ofclaim 1 further comprising separating linear alkylbenzene from thelinear alkylbenzene product stream, wherein the formed dispersioncomprises gas bubbles with a mean diameter of less than 5 μm.
 3. Themethod of claim 2, wherein the separated linear alkylbenzene comprisesdodecylbenzene.
 4. The method of claim 2 further comprising contactingthe aromatic stream with a second catalyst before introducing theolefin, and wherein the mean diameter is less than 1.5 μm.
 5. The methodof claim 2, wherein the separated linear alkylbenzene has the formula:

wherein R is an alkyl group having from 1 to 20 carbon atoms and R maybe branched or unbranched.
 6. The method of claim 1, wherein at leastone of the catalyst and the second catalyst is a Lewis acid, and whereinthe reaction vessel is an alkylation reactor configured for receivingthe dispersion from the shear device.
 7. The method of claim 1, whereinat least one of the catalyst and the second catalyst comprises analuminum halide, a titanium halide, a zirconium halide, an iron halide,a vanadium halide, a chromium halide, and combinations thereof.
 8. Themethod of claim 1, wherein the olefin comprises from 1 to 10 carbonatoms.
 9. The method of claim 1, wherein the shear device comprises atleast one rotor and at least one stator separated by a shear gap in therange of from about 0.02 mm to about 5 mm, and wherein the shear deviceis capable of producing a tip speed of the at least one rotor in therange of greater than about 23 m/s.
 10. A method of producing a linearalkylbenzene comprising: introducing an olefin into an aromatic streamto form a mixture; processing the mixture in a shear device to form adispersion; and reacting the dispersion in the presence of a catalyst ina reactor vessel to form a linear alkylbenzene product stream, whereinthe olefin comprises from 1 to 10 carbon atoms, and wherein the aromaticstream comprises at least one selected from the group consisting ofbenzene, toluene, phenol, aniline, xylene, and ethylbenzene.
 11. Themethod of claim 10, wherein the dispersion comprises olefin gas bubbleswith an average gas bubble diameter of less than about 5 μm.
 12. Themethod of claim 10 further comprising: transferring the linearalkylbenzene product stream to a stripper; and operating the stripper toproduce substantially pure linear alkylbenzene.
 13. The method of claim12 further comprising recycling at least a portion of the linearalkylbenzene product stream or substantially pure linear alkylbenzene tothe shear device, wherein the shear device comprises at least tworotor-stator generators.
 14. The method of claim 10, wherein thecatalyst is selected from the group consisting of hydrofluoric acid andaluminum chloride.
 15. A method of producing a linear alkylbenzene, themethod comprising: introducing one or more olefins into an aromaticstream to form a reactant stream; processing the reactant stream in ahigh shear device to produce a sheared product stream, wherein the sheardevice comprises at least one generator comprising a rotor and acomplementarily-shaped stator; reacting the sheared product stream inthe presence of a catalyst to form a linear alkylbenzene product stream,wherein said linear alkylbenzene is formed at a temperature in the rangeof from about 0° C. to about 60° C.; and separating linear alkylbenzenefrom the linear alkylbenzene product stream.
 16. The method of claim 15,wherein the sheared product comprises gas bubbles with a mean diameterof less than 100 nm.
 17. The method of claim 15, wherein the catalyst isselected from the group consisting of hydrofluoric acid and aluminumchloride.
 18. The method of claim 15, wherein the olefin comprises from1 to 10 carbon atoms, and wherein the aromatic stream comprises at leastone selected from the group consisting of benzene, toluene, phenol,aniline, xylene, and ethylbenzene.
 19. The method of claim 15 furthercomprising recycling at least a portion of the sheared product stream,the linear alkylbenzene product stream, and substantially pure linearalkylbenzene to the shear device, wherein the shear device comprises asecond rotor-stator generator.
 20. The method of claim 15, wherein theseparated linear alkylbenzene has the formula:

wherein R is an alkyl group having from 1 to 20 carbon atoms and R maybe branched or unbranched.